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Plant Physiology and Soils Basic Botany Fall 2007

Plant Physiology and Soils Basic Botany Fall 2007. Brooke Wheeler. Saturday September 22. Reading quiz Plant physiology Short break (talk with project group) Soils- play with dirt Transpiration lab. Plant Physiology. Plant hormones Plant growth and trophisms Photosynthesis.

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Plant Physiology and Soils Basic Botany Fall 2007

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  1. Plant Physiology and SoilsBasic BotanyFall 2007 Brooke Wheeler

  2. Saturday September 22 • Reading quiz • Plant physiology • Short break (talk with project group) • Soils- play with dirt • Transpiration lab

  3. Plant Physiology • Plant hormones • Plant growth and trophisms • Photosynthesis

  4. External factors and plant growth • Light- phototrophism (elongation influenced by auxin) • Gravitropism (auxin concentration) • Thigmotropism- growth response to touching a solid object • Circadian rhythms (ex. leaves moving outward during the day)

  5. Plant Hormones • Chemical signals • Regulators • Stimulate • Inhibit

  6. Auxin • Phototrophism • Elogation of shaded cells bend towards light • Gravitrophism or geotrophism • Upper root cells elongate due to lower levels, causing the root to grow downwards • Promotes adventitious root growth on cuttings • Prevents fruit and leaf abscission • Fruit maturation

  7. Normal All seeds Removed  Auxin promotes fruit development  Horizontal band of seeds removed

  8. Gravitropism

  9. Cytokinin and root gravitropism

  10. Gibberellin • Elongation of shoots • Seed germination • Stimulation of flowering in some plants

  11. Effects of Gibberellin

  12. Thigmotropism -roots around rocks, shoots of climbers around supports -Differential growth rates

  13. Senescence (Aging) You have a bunch of green bananas but your child will only eat a ripe banana. What might to you do in order to speed up the ripening process?

  14. Senescence • Ethylene • Ripening of fruit • Separation process • Breakdown of membranes, softer cell walls • Abscisic acid • Leaf abscission • Fall color? • Dormancy in some seeds

  15. Mutant of maize Zea mays -decreased sensitivity of embryos to abscisic acid leads to premature germination

  16. Diurnal movements Wood sorrel (Oxalis sp.) during day (above) and night (right)

  17. Temperature and Day length

  18. Photosynthesis • Capture of light energy from sun • 250 billion metric tons of sugar/yr • Overall reaction CO2 + H2O + Light energy  (CH2O) + O2

  19. Chloroplast from mesophyll cell of the pigweed, Amaranthus retroflexus

  20. Elodea, pondweed Oxygen on leaves of submerged plant Van Niel first to propose that oxygen came from splitting water, not breakdown of CO2

  21. Electromagnetic Spectrum

  22. Light • Wave model • All radiation travels in waves with distinctive wavelengths • Particle model • Albert Einstein 1905 • Particles of energy compose light (photons) • Energy of a photon is inversely proportional to its wavelength (longer wavelength, lower energy)

  23. Pigments! -substances that absorb light -varying absorption spectrums

  24. Taraxacum officinale Mesophyll specialized for photosynthesis

  25. Structure of chlorophyll a

  26. Stomata in a leaf- need CO2 to diffuse in for photosynthesis

  27. Photosynthesis

  28. Overview of Photosynthesis

  29. C4 photosynthesis- spatial separation • more efficient but higher energy • 5 ATP to fix one molecule of CO2 but C3 plants need 3 ATP • Maintain high ration of CO2 to O2 at sight of Rubisco activity • (Maize, sugarcane, sorghum) • evolved in tropics and are wll adapted to high light, high temp and dryness. CAM: Crassulacean Acid Metabolism • -Cacti, and stonecrops ( family Crassulaceae) • -Photosynthetic cells can fix CO2 in the dark- temporal separation

  30. Sugarcane C4 Pineapple CAM

  31. Soil • Take a break first!

  32. Plant Nutrition

  33. Macronutrients • Sulfur: soil • Phosphorous: soil • Calcium: soil • Potassium: soil • Nitrogen: soil/fungi • Oxygen: air, water • Carbon: air and soil • Hydrogen: air

  34. Micronutrients: from soil • Magnesium • Molybdenum • Copper • Zinc • Manganese • Boron • Iron • (Chlorine, Aluminum, sodium, silicon, cobalt)

  35. Nutrient Cycling

  36. Hubbard Brook Experiments

  37. Legumes contain symbiotic bacteria called rhizobia within nodules in their root systems, producing nitrogen compounds that help the plant to grow and compete with other plants.

  38. Not enough magnesium causes Chlorosis

  39. Soil-an essential part of a plant’s environment-the source of plant nutrition

  40. Soil • Inorganic • Erosion of rock • Organic • Humus • Decomposing plant and animal matter

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